US 20080043076 A1
An ink container is provides ink to a vented printhead, where both the ink container and the vented printhead are positioned on a moveable carriage. The ink container receives ink from an off-carriage ink supply via an ink conduit. Air is removed from the printhead and ink container via a low pressure vacuum pump coupled to the ink container via an air conduit. The low pressure vacuum pump generates low pressure to pull air from the ink container. A higher pressure pump may be used in conjunction with a pressure relief valve that limits the pressure in the ink container.
1. A valve, comprising:
a movable element;
a stationary element;
a flexible thin film that connects the movable element and the frame;
wherein the movable element, the stationary element, the film, and the frame define a fluidic path; and
an actuation member that interacts with the movable element to interrupt a movement of a fluid through the fluidic path.
2. The valve of
3. The valve of
4. The valve of
5. The valve of
6. The valve of
7. The valve of
8. The valve of
9. The valve of
10. The valve of
11. The valve of
12. A method of constructing an apparatus including a valve, comprising:
providing a frame;
affixing a check element to the frame by a flexible thin film that is separate from the frame and the check element;
adding a stop element to abut the check element; and
adding at least one actuation member that abuts the check element and facilitates an actuation of the check element.
13. The method of
14. The method of
15. The method of
16. The method of
17. A valve, comprising:
first and second structures operably attached to the frame, wherein at least one of the first and second structures is movable with respect to the frame;
a flexible thin film affixed to the valve frame and to the movable structure; and
an actuation member that abuts the movable structure and facilitates movement of the movable structure.
The present invention relates generally to inkjet printers, and more specifically, to devices, methods, and systems for removing air from ink containers supplying inkjet printheads.
Ink jet printers are used commonly in offices and home printing applications. They are popular due to their low cost of operation, low energy use and quiet operating features. Ink jet printing involves the ejection of tiny ink droplets through small holes, in a controlled manner, to create the desired image on the media intended to receive the image. Ink is supplied from an ink reservoir to a printhead, which includes various passageways from the reservoir to a plurality of firing chambers having nozzle orifices. Energy is applied to the ink from an ink droplet generator near each orifice, which may include the application of electrostatic attraction, the application of oscillating forces from piezo elements, the application of heat from heating elements or the like.
It is known to provide the nozzle orifices in a printhead cartridge that is mounted on a carriage that may support one or more such printheads. The carriage traverses back and forth across the medium being printed, and ink droplets are emitted as the carriage moves. One of the ways in which ink jet printing can be made faster is simply to move the carriage faster as the ink droplets are emitted. In doing so, it is desirable to minimize the amount of ink contained within the cartridge carried on the carriage, to reduce the weight and thus the momentum of the carriage. Further, the repeated and abrupt reversal in movement direction of the carriage traversing back and forth across the media can create turbulence in the ink, which in turn can cause printing problems due to air absorption, ink foaming and the like.
For some large printing devices, such as plotters used to create drawings, posters or other large printing jobs; or for printers such as color printers and printers designed for high volume print service utilizing large volumes of ink in relatively short time periods, carrying a reasonable volume of ink in the ink cartridge on the carriage has become impractical. If a small volume of ink is carried to reduce weight and momentum of the carriage, frequent change is necessary as the ink supply is rapidly diminished. Alternatively, carrying a large volume of ink in the cartridge makes the cartridge large and heavy, neither of which is desirable for a fast moving carriage.
To satisfy the goal of reducing carriage weight, and to provide adequate ink volumes for printers requiring such, it has been known to provide large volume, off carriage ink reservoirs, which are stationary in the printer. A flexible tube connects the ink reservoir to the ink cartridge on the carriage, and only a small amount of ink need be carried within the cartridge itself.
However, the use of off-carriage ink reservoirs presents its own unique set of problems. It is most often necessary to operate an off carriage ink delivery system at a slight negative or back pressure, to prevent ink dripping from the nozzles. However, back pressure that is too high can result in the printhead becoming deprimed, creating additional printing problems. Further, high back pressure can draw air into the ink supply system, which then can become trapped within the ink, causing even further printing problems.
What is needed is an ink delivery system that overcomes the aforementioned problems by providing for air removal in the system while simultaneously providing ink to a printhead. It would be advantageous for such a system to include a low pressure pump that provides air removal while preventing damage to system components.
In some embodiments of the invention, there is disclosed an apparatus including a valve operable to move from an open state to a closed state. The apparatus includes a frame, a check element affixed to the frame by a flexible thin film that is separate from the frame and the moveable check element, a stop element, where the stop element is operable to abut the check element; and at least one actuation member that abuts the check element to facilitate actuation of the check element.
In some embodiments of the invention, the check element is constructed from a thermoplastic elastomer (TPE). According to another aspect of the invention, both the check element and the flexible thin film are constructed from a thermoplastic elastomer (TPE). According to yet another aspect of the invention, the check element includes a hole through the center of the check element. The stop element may also or alternatively include a hole through its center.
In some embodiments of the invention, the at least one actuation member can include a spring. The frame may also include at least one pass-through hole, which may act as an inlet or an outlet. The frame may additionally retain fluid and/or ink. According to one aspect of the invention, the apparatus includes at least one actuator, separate from the at least one actuation member, operable to assist in moving of the moveable check element. Additionally, the check and/or stop elements may be moveable components to assist in the check element and stop element abutting each other.
In another embodiment of the invention, there is disclosed a method of constructing an apparatus that can include a valve. The method includes providing a frame, providing a check element affixed to the frame by a flexible thin film that is separate from the frame and the moveable check element, providing a stop element, wherein the stop element is operable to abut the check element, and providing at least one actuation member that abuts the check element to facilitate actuation of the check element.
In another of the invention, the check element is constructed from a thermoplastic elastomer (TPE). According to another aspect of the invention, both the check element and the flexible thin film are constructed from a thermoplastic elastomer (TPE). According to yet another aspect of the invention, the check element includes a hole through the center of the check element. The stop element may also or alternatively include a hole through its center.
In yet another embodiment of the invention, the at least one actuation member can include a spring. The frame may also include at least one pass-through hole, which may act as an inlet or an outlet. The frame may additionally retain fluid and/or ink. According to one aspect of the invention, the apparatus includes at least one actuator, separate from the at least one actuation member, operable to assist in moving of the moveable check element. Additionally, the check and/or stop elements may be moveable components to assist in the check element and stop element abutting each other.
Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
The present inventions now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the inventions are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.
The ink container 22 is normally carried on a carriage that traverses back and forth in close proximity to the media upon which the printed image is being formed. The ink container 22 engages the printhead 15, which has an array of nozzles (not shown) from which ink droplets are emitted in the desired pattern and sequence for creating the desired image on the media intended to receive the printed image. As described in greater detail with respect to
It will be appreciated that the ink supply item 12 includes a housing that encloses an ink reservoir (not illustrated), which may be a flexible bladder or the like, as those skilled in the art will readily understand. The ink supply item 12 may also include an outlet (not illustrated) that connects to the ink conduit 20. According to one aspect of the invention, the ink supply item 12 is mounted in a stationary manner in the printing device, and remains in place even as the carriage carrying ink container 22 traverses back and forth during a printing operation. Thus, the ink supply item 12 may be off carriage, as opposed to the ink container 22 and printhead 15, which may be both on carriage. The ink conduit 20 is sufficiently long and flexible to move as required, to maintain fluid flow communication between ink container 22 and ink supply item 12, even as the ink container 22 is moved during printing. According to another embodiment of the present invention, the ink supply item 12 may also be carried on the carriage such that it is on carriage.
As is shown in
The filter 25 provided at the interface of the air conduit and the air removal portion 27 of the ink container 22 is operable to allow air to enter the air conduit 18 while preventing ink from entering the air conduit 18. According to one aspect of the invention, the filter is constructed of a hydrophobic mesh material, such as porous treated polysulphone, treated acrylic copolymers, porous polytetrafluoroethylene, or other treated polymers. Various hydrophobic materials are available from Pall Corporation or Gore Corporation. A suitable hydrophobic material for the filter 25 does not wet easily, and therefore retains a no-liquid pass property even as the material is contacted by ink from within the ink container 22, which can be useful when the ink level within the ink container 22 rises to the level of the filter 25 during operation of the ink delivery system 10. It will be appreciated that while only a single filter 25 is illustrated in the side view of the ink delivery system 10 shown in
Referring again to
Because the ink supply item 12 is positioned at a lower height than the ink container 22 in the ink delivery system 10, the screen's 24 ability to prevent air from entering the ink container 22 prevents the ink within the ink container from draining back into the ink supply item 12. Additionally, it will be appreciated that air is accumulated within the ink container 22 away from the screen 24 to prevent high pressure from developing at the ink supply interface with the printhead 15, which could prevent the printhead 15 from being resupplied with ink.
As described above, the printhead 15 may be a vented printhead, and the ink required for operation will be provided directly from the felt, which receives the ink from the ink container 22. The felt in the printhead 15 can also include and/or be replaced by foam or fibrous materials. Ink used from the felt creates the pressure demand for ink replenishment. A non-vented printhead can have a flexible member to replace the capacitance function of the felt. Additionally, the removal of air from the ink container 22 supply subsystem permits ink to remain against the screen or supplied to the printhead thus keeping the pressure drop low. With this air removal configuration, the ink delivery system 10 can be shipped dry and then primed with ink during a machine initialization process. The air removal stops when ink is against filter 25, at this time the vacuum system only exerts pressure on the filter 25 and no longer on the ink container 22.
It will be appreciated by one of ordinary skill in the art that the height of ink in the off-carriage ink supply item 12 and the backpressure of ink in the felt of a vented printhead 15 are in equilibrium in the ink delivery system 10. Ink flows in or out of the printhead 15 to maintain this equilibrium. As an illustrative example, with all backpressure measured relative to the nozzle plate, if under normal conditions the ink supply item 12 ink fluid height is 4 cm below the printhead chip, then the printhead backpressure will be −4 cmH2O when equilibrium exists. Continuing with this illustrative example, if the printhead backpressure increases to −5 cmH2O then a 1 cmH2O pressure draw to resupply ink to the printhead 15 is created. Ink will continue to flow until this differential is eliminated. The higher the backpressure difference the faster the ink is replenished to the printhead 15.
It will also be appreciated that during normal printing operations ink is supplied by the printhead 15. In the short term the ink is replaced by a combination of ink coming from the ink container 22 and air coming in through a vent in the printhead 15. As air comes into the printhead 15 the backpressure increases and pulls ink through the ink supply path until the air is replaced with ink. The printing and ink resupply system (which includes the ink container 22, ink conduit 20, and ink supply item 12) act asynchronously. The printhead 15 supplies peak flow requirements while the resupply subsystem replenishes ink at a delayed and normally slower rate. Instead of pulling air into the printhead 15 a non-vented printhead supplies part of the ink by changing volume. The volume change increases backpressure and will decrease and reach equilibrium when the ink is re-supplied and the volume returns to normal. A non-vented printhead system without volumetric changes requires all the demand volume to come from outside of the printhead.
Because the pump 13 must not exert too strong of a vacuum, which could damage the filter and result in ink flowing into the air conduit 18, the pressure relief valve 16 permits the use of a stronger pump that would otherwise exert too much pressure in the ink container 22. Thus, the pressure relief valve 16 may be opened while the pump 13 is operating, thereby reducing the suction generated in the ink container 22. As a result, the air removal system 26 shown in
The low pressure pump 29 generally include vacuum, pressure, and actuation sections. To construct the pump 29, a vacuum seal 42 is mechanically attached to the pump body 44 (block 56). An assembly is then made by thermally attaching the film vacuum diaphragm 38 to the vacuum check 40 (block 54). This assembly is then located and sealed to the pump body 44, where the film vacuum diaphragm 38 is formed to make an operational vacuum diaphragm (block 58). The vacuum spring 36 and spring retainer 34 are added to the pump to complete the vacuum seal portion of the pump (block 62). It should be appreciate that this type of check seal can be used for the pressure relief valve described above with respect to
During operation, the actuation diaphragm 30 is flexed as the actuation plate 32 is moved back and forth. The draw stroke (for larger pump volume) opens the vacuum side, while the return stroke opens the pressure side of the pump. During the draw stroke, the vacuum seal 42, vacuum check 40, vacuum diaphragm 38, and vacuum spring 36 are opened when the vacuum differential across the vacuum diaphragm 38 is above its opening force, while the pressure components (46, 48, 50) remain sealed. The return stroke opens the pressure O-ring 46, pressure ball 48, and pressure spring 50 in a similar manner, while the vacuum components (36, 38, 40, 42) remain sealed. To control the maximum vacuum at the ink container 22, the draw stroke of the actuation plate 32 is spring limited. Although the return stroke can be driven back through an external (as illustrated) or internal spring, it may also be driven positively using a cam or the like that is operated by a motor (not illustrated), as is known to those of ordinary skill in the art. The vacuum portion of the system minimizes the valve actuation pressure.
According to one aspect of the invention, polypropylene-based film can be used to create the actuation diaphragm 30 and vacuum diaphragm 38. Additionally, the pump body 44 may be constructed from polypropylene. Similar compatible materials known to those of ordinary skill in the art may alternatively be used and/or substituted. Some other films are polyolefin based, polyethylene based, or multi-layer films. According to another aspect of the invention, the vacuum style section could replace the pressure section to create a lower pressure side of the pump. It will be appreciated that sealing film to multiple components creates low cost, large area diaphragms that may be employed in ink delivery systems of the present invention.
Using an air removal system with a pressure relief valve, as is illustrated in
The diaphragm check valve 70 in
When the diaphragm check valve 70 is in the closed position of
According to one aspect of the invention, the valve 70 shown in
According to another aspect of the invention, the low pressure diaphragm check valve 70 of
In an open state, air passes into an opening 87 on the left source side of the valve 80 passes a gap between the stop element 86 and the check element 88, and passes to the non-source side (to the right of the valve 80) via the path 89. Once this occurs, the pressure increases on the non-source side, decreasing the differential pressure between the source and non-source sides, resulting in a closing of the valve 80. As with the illustrative check valve 70 of
Referring once again to an ink container from which air is removed by the air removal systems described above,
In this design an extra chamber is used to remove air from the system. Therefore, an air receptacle 134 is positioned in the ink container 129, which receives an air conduit (not illustrated) that pumps air out of the ink chamber 129. The air conduit may be received into a conduit receptacle within or connected to the air receptacle similar to the ink conduit receptacles 136 a, 136 b, 136 c, 136 d. As described in detail below, the air receptacle 134 includes an air removal opening in the ink container 129 that receives air from each of the ink reservoirs 130 a, 130 b, 130 c, 130 d, specifically, from air drains 132 a, 132 b, 132 c, 132 d that are integrated into the ink container 129.
Each air drain 132 a, 132 b, 132 c, 132 d is exposed to, or open to, an associated ink reservoir and permits air from the ink reservoir to flow through a respective filter (not illustrated) to the air conduit (not illustrated) via the air receptacle 134. According to one aspect of the invention, the air drains 132 a, 132 b, 132 c, 132 d may be covered by one or more filters that prevent the flow of ink within the reservoirs 130 a, 130 b, 130 c, 130 d into the air conduit. The back side of the ink container 129 of
As shown in
For illustrative purposes, the general location of the ink reservoirs 130 a, 130 b, 130 c, 130 d are illustrated with dashed lines in
It will be appreciated that ink from the printhead will wet the one or more screens such that a large quantity of air will not pulled into the ink container from the printhead. Thus, the pump, which may be a low pressure vacuum pump, is actuated as many times as required (blocks 186, 188) to remove the air from the ink container and replace it with ink. This ink comes primarily from the ink supply item although initially a small amount comes from the printhead. Air stops being removed from the system when ink covers the filters (block 190). Additional pump actuation does nothing to the system since the pressure generated is limited so ink is not pulled through the filters. To achieve backpressure equilibrium between the printhead and off carrier ink source, ink may either come into or leave the printhead. Periodic actuation of the pump can remove any air that may accumulate over time.
Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.